Global Geological And Climatic Events

[pib] River erosion in Ladakh Himalayas

Note4Students

From UPSC perspective, the following things are important :

Prelims level : Himalayan rivers, Zanskar Padam

Mains level : Read the attached story

Indian researchers have studied rivers in Ladakh Himalaya, bringing out 35 thousand-year histories of river erosion and identified hotspots of erosion and wide valleys that act buffer zones.

Click here to read more about the Himalayan river systems and its orogeny

Erosion hotspot: Ladakh region

  • The Ladakh Himalaya forms a high altitude desert between Greater Himalayan ranges and Karakoram Ranges.
  • The Indus and its tributaries are major rivers flowing through the terrain.
  • The Zanskar River is one of the largest tributaries of the upper Indus catchment, draining orthogonally through highly deformed Zanskar ranges.

Zanskar: A major river in Ladakh

  • Two prominent tributaries of Zanskar River are the Doda and Tsrap Lingti Chu, which confluence at Padam village in the upper valley to form the Zanskar River.
  • Zanskar catchment was explored to understand the landform evolution in the transitional climatic zone, using morpho-stratigraphy and study of landforms like valley fill terraces, alluvial fans (triangle-shaped deposit of gravel, sand, and even smaller pieces of sediment, such as silt).

Zanskar Padam

  • Zanskar river makes a deep gorge in its lower reaches with the headwaters in upper Zanskar makes wide basin called as Padam.
  • The basin stores large amount of sediments in form of fans and river terrace deposits
  • The research suggested that the wide valley of Padam, with an area of 48 square km, in the upper Zanskar, has stored a vast amount of sediments in these landforms.
  • Thus Padam valley is a hotspot of sediment buffering in the Zanskar.

Sediment study reveals the erosion

  • The study suggested that most sediments were derived from Higher Himalayan crystalline that lies in the headwater region of Zanskar.
  • It was found out that dominant factors responsible for sediment erosion were deglaciation and Indian Summer Monsoon derived precipitation in the headwaters despite the presence of a geomorphic barrier (the deep, narrow gorge).

Significance of the study

  • The scientists have traced where the rivers draining Himalaya and its foreland erode the most and identify the zones that receive these eroded sediments and fill up.
  • The study will help understand river-borne erosion and sedimentation, which are the main drivers that make large riverine plains, terraces, and deltas that eventually become the cradle to evolving civilizations.
  • It will also help study the dynamics of devastating floods created by these Himalayan rivers in recent times.
  • Thus, the understanding of water and sediment routing becomes crucial while developing infrastructure and for other development works in the river catchment area.
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